1. Field of the Invention
The present invention relates to a sensor for a washing machine, and more particularly, to a sensor for detecting both a water level and a vibration in a washing machine, which permits detection both of the water level of washing water in a washing tub and the vibration of the washing tub.
2. Background of the Related Art
In general, the washing machine removes contaminant on laundry by conducting a washing, rinsing, spinning cycles in succession. In detail, the washing cycle is a process for separating the contaminant on the laundry by friction between washing water and the laundry caused by water circulation using water circulation producing means, such as a pulsator, and softening action of detergent. And, upon completion of the washing cycle, the rinsing cycle is conducted, in which contaminated water is discharged to outside of the washing machine, fresh water is supplied to the washing tub, and the pulsator is rotated to rinse the laundry. Upon completion of the rinsing cycle, the spinning cycle is started. That is, a motor is rotated at a high speed, to discharge water remained in the laundry to outside of the washing tub by using a centrifugal force.
In the meantime, a water level in the washing tub, quantity of detergent to be used, and a total washing time period are determined in general with reference to an amount of laundry introduced in the washing tub in the conduction of the washing cycle. Once an appropriate water level is determined with reference to the amount of laundry, the washing water is supplied to the washing tub until the washing water reaches to the set water level before the washing cycle or the rinsing cycle is started. In this instance, the water level in the washing tub is detected by means of a water level sensor.
In the meantime, it is unavoidable that vibration and noise are occurred in the spinning cycle as the washing tub spins at a high speed ranging around 1700 rpm. Therefore, in order to attenuate the vibration, vibration attenuation means, such as snubber bar, is provided between the washing tub and the washing machine case. However, in fact it is impossible to absorb the entire vibration generated in the high speed rotation by means of the vibration attenuation means. Therefore, recently, a vibration detection sensor is used for detecting the vibration of the washing tub generated during the spinning cycle, for controlling processing of the spinning cycle according to a degree of the vibration. A related art water level detecting sensor and a related art vibration detecting sensor will be explained.
First, a related art washing machine and a water level detecting sensor will be explained with reference to FIG. 1 and 2. There is an outer tub 5 inside of a washing machine case 1, a washing and spinning tub(hereafter called as xe2x80x9cwashing tubxe2x80x9d) 3 rotatably mounted in the outer tub 5, and a pulsator inside of the washing tub 3 rotated by a motor 9. And, there is a snubber bar 6 for attenuating the vibration between the outer tub 5 and the case 1. And, there is a feed water valve 7 above the washing machine case 1, and a drain valve 8 connected to the outer tub 5. There are a water level detecting sensor 10 and a vibration detecting sensor 20 on an upper portion of the washing machine case 1.
The water level detecting sensor will be explained in detail with reference to FIGS. 2A, 2B and 3.
The water level detecting sensor 10 is provided with a hydraulic pressure transmission means, such as bellows 12 and diaphragm 12a, in a lower portion of a cylindrical housing 11, a body of the water level detecting sensor 10, for expanding and contracting in up and down direction on reception of a hydraulic pressure generated by the water level of the washing tub. That is, there is a hydraulic pressure transmission passage 5a formed between the hydraulic pressure transmission means and the outer tub 5, for converting the water level of the washing tub and transmitting to the hydraulic pressure transmission means. There is a coil part 15 having a coil with an inductance on an inside wall of the housing 11, and a core holder 13 under the coil part 15 for accommodating a core 14 which moves in an inside space of the coil part 15 in an up and down direction for varying the inductance of the coil 15a. And, there is a cap 18 over the coil part 15, and a spring 16 between the cap 18 and the core 14. That is, when the bellows 12 expands or contracts, the core 14 and the core holder 13, interlocked with a movement of the bellows 12, move within a hollow of the coil part 15 in an up and down direction, with the inductance of the coil 15a varied.
The operation principle of the water level detecting sensor will be explained.
The coil 15a of the coil part 15 is connected to an LC resonance circuit 10a, an output terminal of which is connected to a microprocessor 2. The microprocessor 2 controls the feed water valve 7 and the drain valve 8 with reference to a water level the water level detecting sensor senses. In the washing cycle, the water level is fixed according to an amount of the laundry, and the feed water valve 7 is opened to supply water to the washing tub 3. During water is supplied to the washing tub 3, a hydraulic pressure for the water level is transmitted to the hydraulic pressure transmission means, such as the diaphragm 12a, through the hydraulic pressure transmission passage 5a, to cause the diaphragm 12a to expand or contract in proportion to the transmitted hydraulic pressure. That is, as water is supplied to the washing tub 3, the diaphragm overcomes an elastic force of the spring 16 to expand upward, along with the core 14 on the core holder 13 through the hollow in the coil part 15. Then, the movement of the core 14 varies the inductance of the coil 15a, and the inductance variation of the coil 15a is converted into a predetermined resonance frequency at the LC resonance circuit 10a. The microprocessor 2 determines the water level in the washing tub with reference to a variation of the resonance frequency. When the measured water level reaches to a preset water level, the feed water valve 7 is closed, to stop water supply, and the motor is put into operation for conducting the washing cycle.
In the meantime, upon completion of the washing cycle, contaminated water in the washing tub is drained, and completion of the drain is also detected by using the water level detecting sensor 10. That is, as the drain proceeds, the water level in the washing tub drops, to permit the diaphragm 12a to return to an initial position by the elastic force of the spring 16. Accordingly, the core holder 13 having the core 14 mounted thereon also moves downward to an initial position. If the core 14 returns to the initial position, the inductance of the coil part 15 is also reduced, and the reduced inductance is converted into a resonance frequency at the LC resonance circuit 10a, with reference to which a drain completion time is determined.
A related art vibration detecting sensor will be explained, with reference to FIGS. 1 and 4. There are one pair of contacts 24 and 25 on the washing machine case 1, and a switch leg 22 rotatably fitted under the contacts 24 and 25 for open or closing the contacts 24 and 25, electrically. And, there are one pair of springs 23 under the switch leg 22.
The operation of the vibration detecting sensor will be explained with reference to FIGS. 3 and 4. During washing, particularly, during spinning, if the washing tub hits the switch leg 22 of the vibration detecting sensor 20 due to severe vibration of the washing tub, the switch leg 22 overcomes the elastic force of the spring 23, and rotates in a counter clockwise direction on the drawing, to short the contacts 24 and 25. Upon occurrence of an electrical signal at any one of the pair of the contacts 24 and 25, the microprocessor 2 determines that there is a vibration occurred. According to this, the drain valve 7 is opened for a preset time period, for supplying water to the washing tub, so that the laundry is disposed, not to one side, but evenly, for reducing the vibration. Once the vibration is reduced, the motor 9 is rotated at a high speed, to process the spinning. If there is the electrical signal occurred at the contacts 24 and 25 even after the vibration reducing process continuously, the motor 9 is stopped, for preventing danger coming from an excessive vibration beforehand.
However, the related art water level detecting sensor and the vibration detecting sensor have the following problems.
First, the use of the individual water level detecting sensor and the vibration detecting sensor causes a production cost high. And, the separate fitting of the two sensors require much assembly man-hour.
Second, the related art vibration detecting sensor has difficulty in fitting, and detecting the vibration accurately in view of the structure. Because, if the switch leg is fitted close to the outer tub, the vibration sensor may detect a slight vibration, to cause unnecessary operation, and if the switch leg is fitted far than required, the vibration sensor can detect the vibration only after the vibration becomes very severe. In order to solve such a problem, an accurate vibration amplitude W of the washing tub should be known, which is impossible in fact. And, even if the switch leg is fitted appropriately, the employment of mechanical contacts and spring in the related art vibration detecting sensor requires to re-adjust a gap between the contacts and the switch leg after a prolonged use of the washing machine, and involved in deterioration of a reliability. Because the contacts may rust, or the elastic force of the spring may degrade from the prolonged use.
Accordingly, the present invention is directed to a sensor for detecting both a water level and a vibration in a washing machine that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a sensor for detecting both a water level and a vibration in a washing machine, in which one sensor can detect both a water level and a vibration.
Other object of the present invention is to provide a sensor for detecting both a water level and a vibration in a washing machine , which permits an accurate vibration detection and has a long lifetime.
Another object of the present invention is to provide a sensor for detecting both a water level and a vibration in a washing machine, which can be fitted easily, and permits reduction of a production cost.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the sensor for detecting both a water level and a vibration in a washing machine includes a housing which is a body of the sensor for detecting both the water level and the vibration, hydraulic pressure transmission means under the housing for moving up and down by a hydraulic pressure of the water level in a washing tub, a coil part above the hydraulic pressure transmission means having a coil with a proper inductance, a core holder on the hydraulic pressure transmission means having a core accommodated therein, the core adapted to move up and down within the coil part for varying the inductance of the coil, a cap fitted to a top portion of the coil part, a spring placed in a hollow of the coil part, and a vibration detecting means adapted to move according to the vibration of the housing for varying the inductance of the coil, whereby detecting the water level in the washing tub by substantially varying the inductance of the coil with the up and down movement of the core during a washing cycle or a rinsing cycle, and substantially detecting the vibration of the washing tub by varying the inductance of the coil by means of the vibration detecting means during a spinning cycle.
The vibration detecting means includes a rolling body for substantially moving up and down interlocked with the vibration of the washing tub for varying the inductance of the coil, and a rolling body supporting member having a sloped surface with an angle for accommodating the rolling body.
And, preferably, the rolling body supporting member includes an inserting member on a bottom, and the core holder includes a coupling member for mechanically inserting and coupling the inserting member thereto.
And, preferably, the slope surface of the rolling body supporting member includes a barring surface substantially vertical to the slope surface for inhibiting movement of the rolling body for a minute vibration
Accordingly, the sensor for detecting both a water level and a vibration in a washing machine of the present invention permits detection of both the water level and the vibration by means of one sensor, and the sensor also permits an accurate detection of the vibration.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.